Light-Based Therapy for Arthritis
Eliminate a painful bout of arthritis with nothing more than a non-toxic light-based therapy? Is that really possible?
We’re so accustomed to thinking of anti-inflammatory drugs as the best way to handle this painful condition that it’s hard to imagine equally effective alternatives. But this is indeed the case, and recent research suggests we may benefit from the use of non-toxic, light-based methods.
Arthritis is the medical term for inflammation of the joints, and there are many variations of this disease. One of the most severe types, rheumatoid arthritis, is an autoimmune disorder whereby the body’ s immune system attacks the thin membrane that lines the joints. Like other forms of arthritis, rheumatoid arthritis involves chronic inflammation as well as substantial pain and stiffness in the joints, eventually resulting in severe disability and even deformity in the hands and feet.
While there’s little doubt that the medications commonly used to treat rheumatoid arthritis—NSAIDs, corticosteroids, and methotrexate—can be effective in reducing pain and other symptoms of inflammation, these medications come with a host of adverse side effects and long-term complications. Habitual use of NSAIDs, for example, can lead to dangerous ulcers in the stomach, and long-term use has been linked with an increased risk of heart failure. Methotrexate can result in an increased risk of infection, dizziness, fatigue, and fever. Corticosteroids, by suppressing immunity, can raise the risk of severe infections.
It stands to reason that use of these medications should be minimized when equally effective alternative therapies are available for treating arthritis. Given the side effects and risks associated with long-term use, doctors have begun to turn their attention to safer therapeutic strategies that could be of value in these situations.
Photodynamic Therapy for Arthritis
Although many physicians believe that only conventional medications can stop the progression of these arthritic conditions, there is increasing evidence that photodynamic therapy, or PDT, can have an impact as well. PDT has several effects on the body that could reap therapeutic dividends for people suffering from arthritis.
In the course of rheumatoid arthritis, the joints (such as those found in the hips, knees, feet and hands) are commonly destroyed by changes in the synovial membrane. This membrane is a soft connective tissue found around the joint area that secretes the synovial fluid, which fills the joint cavity and helps cushion and lubricate the joint. A surgical procedure called synovectomy is often done to remove the inflamed joint tissue that is causing unacceptable pain or limiting one’s functioning and range of motion.
When scientists study the inflamed synovium, they notice that the blood vessel supply that supports this membrane appears to be disorganized. Using agents that block the production of new blood vessels (angiogenesis) appears to help curb the development and progression of arthritis. One of the reasons PDT may be effective against arthritis is that it’s capable of inhibiting the formation of new blood vessels around the joint area.
Another effect of PDT, at least when delivered at a low intensity, is to modulate the production of inflammatory chemicals, or cytokines, that account for many of the painful symptoms of arthritis. Indeed, low-intensity PDT can significantly reduce the body’s secretion of IL-6 (a key pro-inflammatory cytokine) while boosting the production of IL-10, an anti-inflammatory cytokine, as reported in the May 2015 issue of Expert Review of Clinical Immunology.
What the Research Shows
According to Dr. Aurélie Reinhard and colleagues at the University of Lorraine in Vandoeuvre-lès-Nancy, France, a number of laboratory studies have evaluated the efficacy of PDT as a treatment for arthritis. Various animal models for arthritis have been studied and different photosensitizers and light treatment protocols have been tried. Light can be delivered to the joint areas with the help of optical fibers. The photosensitizer can be administered either intravenously or directly into the joint area, or both.
One of the earliest studies, conducted in 1994, found that PDT prevented the classic signs of arthritis in mice, such as evidence of cartilage erosion and bone destruction. Other studies showed that PDT prevented inflammation and moreover staved off the more severe stages of arthritis. Small quantities of the photosensitizer were found in the cartilage but not in the adjoining muscle tissue.
Overall the research indicates that various photosensitizers are capable of becoming localized or concentrated in the inflamed joint tissue (synovium), resulting in PDT’s ability to selectively destroy that tissue without the need for surgery. No damage to the healthy, non-inflamed connective tissues or structures (such as the ligaments, menisci and cartilage) has been reported as a result of PDT, and side effects have been minimal.
A study at the Hamamatsu University School of Medicine in Hamamatsu, Japan, demonstrated that PDT with the photosensitizer Laserphyrin (talaporfin sodium) was an effective treatment for the arthritis in both humans and laboratory animals. The effectiveness of the Laserphyrin-PDT depended on the concentration of the photosensitizer as well as the laser light dose, as reported in the June 2008 issue of Clinical Rheumatology.
Other research suggests that encapsulating the photosensitizer in a “liposome”—a casing of phospholipid molecules that enables more effective transport of the medicine into the tissues—can result in even more better treatment outcomes. Taken together, these studies suggest PDT could be a potential new clinical treatment for arthritic joints, without the adverse effects that accompany mainstream medications and surgeries for this debilitating condition.
Some of the most cutting-edge studies of this issue have been conducted by Dr. Michael Hamblin and colleagues at Harvard Medical School and the Wellman Center for Photomedicine in Boston, Massachusetts (USA). Hamblin’s studies focused on bacteria-induced arthritis in animals. They found that the photosensitizing agent called Methylene blue was optimal for killing the bacteria while preserving key immune cells (neutrophils). PDT with the agent, methylene blue, was quite effective when injected into the joint tissue before the light treatment. Moreover, it protected the mice against a subsequent bacterial challenge, thus preventing the return of arthritis after completing the treatment. The neutrophils themselves appear to play an important role in PDT’s ability to protect against the development of arthritis.
In summary, the research to date suggests that, whereas high-intensity PDT destroys tumors, low-intensity PDT can eliminate infections and inflammation. “PDT presents several potential applications in non-oncological disorders, but so far, it is only approved in cancers,” Dr. Reinhard and her colleagues state in the report for Expert Review of Clinical Immunology. “Thus, clinical trials are needed to find its scope in inflammatory and infectious conditions.”
Next week, we will explore how PDT can serve as a beneficial treatment for another common inflammatory problem: colitis, or inflammation of the colon.
Sources
Reinhard A, Sandborn WJ, Melhem H, Bolotine L, Chamaillard M, Peyrin-Biroulet L. Photodynamic therapy as a new treatment modality for inflammatory and infectious conditions. Expert Rev Clin Immunol. 2015 May;11(5):637-57.
Torikai E1, Kageyama Y, Kohno E, Hirano T, Koide Y, Terakawa S, Nagano A. Photodynamic therapy using talaporfin sodium for synovial membrane from rheumatoid arthritis patients and collagen-induced arthritis rats. Clin Rheumatol. 2008 Jun;27(6):751-61.
Love T, Solomon DH. The relationship between cancer and rheumatoid arthritis: still a large research agenda. Arthritis Res Ther. 2008;10(3):109.
Tanaka M, Mroz P, Dai T, Huang L, Morimoto Y, Kinoshita M, Yoshihara Y, Nemoto K, Shinomiya N, Seki S, Hamblin MR. Photodynamic therapy can induce a protective innate immune response against murine bacterial arthritis via neutrophil accumulation. PLoS One. 2012;7(6):e39823
Tanaka M, Kinoshita M, Yoshihara Y, Shinomiya N, Seki S, Nemoto K, Hamblin MR, Morimoto Y. Photodynamic therapy using intra-articular Photofrin for murine MRSA arthritis: biphasic light dose response for neutrophil-mediated antibacterial effect. Lasers Surg Med. 2011 Mar;43(3):221-9.
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